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<head>
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    <title>Document</title>
    <script>
        <!--同时声明多个变量，但不赋值-->
        var myName,age,Stu_id;
        <!--同时声明多个变量，并且赋值-->
        var myName = '小杨',
            age = 18;
            Stu_id = '01';
    </script>
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<body>
    
</body>
</html>